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我正在尝试为 GNU 无线电中的 Analog Discovery 2 示波器实现自定义源块。我已经有一个可用的 python 脚本来记录来自 Analog Discovery 2 设备的样本到 WAV 文件（问题末尾的代码）。

我希望能够直接在 GNUradio 伴侣中连接这个示例源。我按照官方教程创建自定义块来为我的块生成模板代码：

import numpy
from gnuradio import gr

class AnalogDiscovery2(gr.sync_block):

    def __init__(self, sample_rate):
        gr.sync_block.__init__(self,
            name="Analog Discovery 2",
            in_sig=None,
            out_sig=[numpy.float32])
        self.sample_rate = sample_rate


    def work(self, input_items, output_items):
        out = output_items[0]
        # <+signal processing here+>
        out[:] = whatever
        return len(output_items[0])

我知道我必须修改work函数来获取样本并将它们复制到out变量中，但是我想知道如何调整采样率？我不知道该work函数是如何调用的，以及它的时间是什么。如何设置采样率？

将样本记录到 WAV 文件中的 Python 代码：

from ctypes import *
from dwfconstants import *
import math
import time
import matplotlib.pyplot as plt
import sys
import wave
import struct

if sys.platform.startswith("win"):
    dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
    dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
    dwf = cdll.LoadLibrary("libdwf.so")

#declare ctype variables
hdwf = c_int()
sts = c_byte()
hzAcq = c_double(48000)
nSamples = 96000
rgdSamples = (c_double*nSamples)()
cAvailable = c_int()
cLost = c_int()
cCorrupted = c_int()
fLost = 0
fCorrupted = 0

#print DWF version
version = create_string_buffer(16)
dwf.FDwfGetVersion(version)
print "DWF Version: "+version.value

#open device
print "Opening first device"
dwf.FDwfDeviceOpen(c_int(-1), byref(hdwf))

if hdwf.value == hdwfNone.value:
    szerr = create_string_buffer(512)
    dwf.FDwfGetLastErrorMsg(szerr)
    print szerr.value
    print "failed to open device"
    quit()

print "Preparing to read sample..."

#print "Generating sine wave..."
#dwf.FDwfAnalogOutNodeEnableSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_bool(True))
#dwf.FDwfAnalogOutNodeFunctionSet(hdwf, c_int(0), AnalogOutNodeCarrier, funcSine)
#dwf.FDwfAnalogOutNodeFrequencySet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(1))
#dwf.FDwfAnalogOutNodeAmplitudeSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(2))
#dwf.FDwfAnalogOutConfigure(hdwf, c_int(0), c_bool(True))

# enable positive supply
dwf.FDwfAnalogIOChannelNodeSet(hdwf, c_int(0), c_int(0), c_double(True)) 
# set voltage to 3 V
dwf.FDwfAnalogIOChannelNodeSet(hdwf, c_int(0), c_int(1), c_double(3.0)) 
# enable negative supply
dwf.FDwfAnalogIOChannelNodeSet(hdwf, c_int(1), c_int(0), c_double(True)) 
# set voltage to -1 V
dwf.FDwfAnalogIOChannelNodeSet(hdwf, c_int(1), c_int(1), c_double(-1.0)) 
# master enable
dwf.FDwfAnalogIOEnableSet(hdwf, c_int(True))

#set up acquisition
dwf.FDwfAnalogInChannelEnableSet(hdwf, c_int(0), c_bool(True))
dwf.FDwfAnalogInChannelRangeSet(hdwf, c_int(0), c_double(0.1))
dwf.FDwfAnalogInAcquisitionModeSet(hdwf, acqmodeRecord)
dwf.FDwfAnalogInFrequencySet(hdwf, hzAcq)
dwf.FDwfAnalogInRecordLengthSet(hdwf, c_double(nSamples/hzAcq.value))

#wait at least 2 seconds for the offset to stabilize
time.sleep(2)

#begin acquisition
dwf.FDwfAnalogInConfigure(hdwf, c_int(0), c_int(1))
print "   waiting to finish"

cSamples = 0

while cSamples < nSamples:
    dwf.FDwfAnalogInStatus(hdwf, c_int(1), byref(sts))
    if cSamples == 0 and (sts == DwfStateConfig or sts == DwfStatePrefill or sts == DwfStateArmed) :
        # Acquisition not yet started.
        continue

    dwf.FDwfAnalogInStatusRecord(hdwf, byref(cAvailable), byref(cLost), byref(cCorrupted))

    cSamples += cLost.value

    if cLost.value :
        fLost = 1
    if cCorrupted.value :
        fCorrupted = 1

    if cAvailable.value==0 :
        continue

    if cSamples+cAvailable.value > nSamples :
        cAvailable = c_int(nSamples-cSamples)

    # get samples
    dwf.FDwfAnalogInStatusData(hdwf, c_int(0), byref(rgdSamples, 8*cSamples), cAvailable)
    cSamples += cAvailable.value


print "Recording finished"
if fLost:
    print "Samples were lost! Reduce frequency"
if cCorrupted:
    print "Samples could be corrupted! Reduce frequency"

#f = open("record.bin", "w")
#for v in rgdSamples:
#    f.write("%s\n" % v)
#f.close()

# Write samples to file
wav_output = wave.open('record.wav', 'w')
wav_output.setparams((1, 2, 48000, nSamples, 'NONE', 'not compressed'))
values = []
for v in rgdSamples:
    packed_value = struct.pack('h', 32768*v)
    values.append(packed_value)

value_str = ''.join(values)
wav_output.writeframes(value_str)
wav_output.close()
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1 回答 1

2

你有一个误解。

采样率对于 GNU Radio 来说不是一个有意义的概念。GNU Radio 块被尽可能快地调度；这意味着重复调用源块，直到输出缓冲区已满。

“挂钟”与处理样本的速度无关。

例如，信号源仅使用有关采样率的信息来计算一段时间内的采样数。正弦有。信号源配置为以 500 的采样率产生频率为 10 的正弦波，其价格与您将其配置为频率为 50 且采样率为 2500 的采样率完全相同。绝对没有行为差异。

我只能强调 GNU Radio 根本没有采样率的概念。块之间传递的信号只是数字序列。原始音频以特定速率采样的事实可能是正确参数化处理样本的块所必需的，但这不是样本固有的。

顺便说一句，没有理由编写自己的 wav 文件源：gr-audio 已经包含一个。

于 2016-10-20T17:50:27.747 回答